Patent DE-102009035922-A1 (DE)
Title: Gas-shielded welding with time-varying shielding gas supply, comprises regulating a regulating device, by which a protective gas volume flow is temporally changed according to a set-point value, to a control value using a control circuit
Inventor: BUERKNER GUNNAR
IPC: B23K9/095
Filed: 2009-08-03
Abstract: The method comprises regulating a regulating device (11), by which a protective gas volume flow is temporally changed according to a first set-point value, to a first control value using a first control circuit (1), and regulating the first control value to an adapted control value using a second control circuit (2), where the adapted control value is based on a second set-point value, which is determined in the second control circuit based on the previous control value or previously adapted control value. The first control circuit has a first pulse generator. The method comprises regulating a regulating device (11), by which a protective gas volume flow is temporally changed according to a first set-point value, to a first control value using a first control circuit (1), and regulating the first control value to an adapted control value using a second control circuit (2), where the adapted control value is based on a second set-point value, which is determined in the second control circuit based on the previous control value or previously adapted control value. The first control circuit has a first pulse generator, which produces the first set-point value. A time clock of the first control circuit is synchronized with a time clock of the second control circuit. The second control circuit has a second pulse generator, which produces the second set-point value, where both pulse generators are operated with same frequency as input parameter. The first pulse generator is operated for producing the first set-point value with extreme values of (minimum, maximum) of a temporal flow function as input parameters. The second pulse generator is operated for producing the second set-point value with further input parameter, which is determined based on the previous control value or previously adapted control value. The second set-point value is transferred into a second control value using an adaptation parameter or an adaptation function. The second control value is calculated with the first control value for producing the adapted control value. The first and second control values are added with one another. The first set-point value is transferred into a regulator-specific guiding parameter using a scaling parameter or a scaling function. The protective gas volume flow is directly or indirectly determined using a measuring device (10) and is fed as actual value of a proportional-integral-derivative regulator of the regulating device. A regulation difference between the actual value and the first set-point value is transferred from the regulator into the first control value. The adapted control value is fed to an actuator (9), by which a gas flow quantity and gas composition of the protective gas volume flow are changed over the time. The regulating device comprises a first actuator, which is connected with a first protective gas source and regulates a first protective gas volume flow, and a second actuator, which is connected with a second protective gas source and regulates a second protective gas volume flow. A ratio of the both protective gas volume flows is set by the adapted control value, which is fed to the both actuators.